Profile of Protos Angelus

Penals are in the best spot they have been since ever. Not OP, not UP, a quick AT squad if you need one. Stop with all this BS about penals being UP or useless or not needed. 3x PTSR on them is great.

So what's your suggestion then?
Make if more fragile but buff its damage?

Your arguments are fairly incoherent. The target size difference is small to almost negligible for shooting on the move. SOV and UKF have a 0.5 moving modifier, so the actual difference is effectively 1 target size.
Also the "small tiny M10" is actually not that small, I don't know where you get that from.

Mobility. Acceleration/max speed. Comparing 105mm and Brummbar, the 105mm has better mobility and a turret but worse AOE/survivability, so trade-offs are fine. However, given how brummbar can reach 312 armour with 800 hp and a mini nuke dispenser, it should be less mobile. That's all I think.
M10 tiny as in weak/low hp. The whole point of M10 is to be extremely mobile for hit and runs but due to it's slow turret rotation it falls flat hard, but that ain't the point of this thread.

So to sum up, I'd only nerf the acceleration/speed on the brummbar, and in return, buff rotation. That would be a buff for smaller modes and a nerf for larger (where it's more dominant).
Most 3v3+ maps don't care about having a turret or not since they are extremely lane-y and there is a massive lack of flanking pathways, especially given how 222 and pios have dominant sight for any flanking attempts.

EDIT: Shame I didn't put the replay where I did win a game, but it was sort of a Pyrrhic victory. A brummbar just drove up to double AT guns which were spread out for at least 25 range or so (on average we had better map control throughout the game), bounced 5 shots, took out both AT guns and snared outran the zook carrying echelons with low HP. Now that was bad RNG, sure, but it's not some rare RNG. I've had plenty of such scenarios against the brummbar. The only reason why it got out alive was the fact that it could outrun infantry with handheld AT weapons. Panther and P4s should outrun infantry even when snared, but a brummbar/105mm/ST/priest/... should not.

This is about the Coh2 Brummbar

I've also just noticed that it has 260 armour with a target size of 22 making it one of the most efficient armour/target size ratio vehicle out there. Its better than Tiger and the Easy 8. The only ones beating it are King Tiger, and super heavy tank destroyers. With vet 2, it gets better than the ISU-152.

I would like to hear the reason why the previous 260 to 240 armour nerf on the Brummbar was rolled back. Very rarely do patch changes get rolled back. That one would probably have been for the better. Its too durable and gets even more durable when vetted up.

Probably sturmpanther played OST and the brummbar didn't bounce 10 shots against a wall of AT guns so they decided "you know, brummbar is UP now"
Brummbar is not OP at the moment, nor is it UP but it's survivability and target size are laughable.
I mean, Jackson has a target size of 24, meaning you can dive it and shoot it on the move. Brummbar, being a fu**ton larger vehicle has a TS of 22, with 260+ armour, ton of HP and not bad mobility considering how heavy/turret-less it is. Heck, it can backpedal faster with the engine damage than infantry can run. At vet3 it has 6.8 max speed, more than Jackson, and closely the same amount as the M10 TD at vet1 (and same target size as the small tiny M10 TD).

Because they aren't stock and take up an entire commander ability slot, unlike the T-70's ability.

Their downside is only becoming active while being stationary, which isn't something you want to do with your tanks in CoH2's highly mobile gameplay. So unlike abilities like the T-70 recon mode, you can only use them defensively. And in order to be powerful (arguably overpowered but that's up for debate) on recon units (222/251) you need to get them to vet 2 and 3 first to get any additional benefits over regular vehicles, so there is a significant investment involved and you need to keep them alive. Without their veterancy sight bonus, spotting scopes offer no special benefits for recon units compared to regular vehicles.

Being stationary is not a downside for OST, not really. 222 can easily be vetted up to 3 in 3v3+. Either by harassing on some wide open maps like steppes or by shooting down planes.
E8 takes up a command slot and is still a useless tank in all but 1v1s (as far as I see, it's great there). Spotting scopes are not really used in 1v1s since being static there is a no-no for any faction. Although can help when expecting an attack. I've often seen vetted 222s parked in safe spots just spotting with 70 range. And chasing it can be disastrous:
a) you're diving a light vehicle with 18/16 target size
b) you're diving against a faction that has stock access to mines, widest arc MG and longest snare (aside from fussies).
Probably the best scout mechanic that was implemented was in Age of Mythology, Atlantis faction those Oracle guys. When they stood still, the vision would be improved in increments. Move and you lose all of it and have to start again. That way you can't just move a bit and stand still again and have 70 vision.
All you said is legit, but stretched. There are plenty of command abilities that take up a slot and are near useless in both axis and allies.

Rifle company new halftrack (don't know why you didn't add the mortar ht but ok)
Cav rifles being 1CP
OST reserve armies, urban pgrens being 2cp (never should have existed and instead should have been some other pgren version)
Soviets with the no-income booby traps, conscript/penal repair tactics, partisans, 45mm at gun

Just to name a few. The RAM + offmap combo has been nerfed although it was doctrinal and the only way soviets can kill something extra heavy, not to mention the 99% chance of losing the T34. Now, soviets can only kill extra heavies in teamgames if they coordinate well AF.
What are you explanations for those?

Don't use pak43 on wide open maps. Use it on maps with lots of buildings and shot/sight blockers because pak43 can AUTOMATICALLY shoot through:
Smoke
Sight-Blocker
Shot-Blocker
... meaning stuff like major arty needs vision and sometimes the single pass of the recon plane is not enough as the planes are quite fast (need to react lightning fast). Pak43 will shoot through 10 buildings to fully damage the tank if there is vision.