I got the chance to use the BTR-70 recently and noticed a glaring issue (so glaring that I'm not sure why it's not present as a ticket here already, TBF)
The viewports do not work - they exist, sure, but they're fully black and don't allow anyone to see anything through them. It's a particular issue with the BTR-70 specifically as, in order to see *anything*, the crew needs to open the shields, exposing the unarmored glass underneath them, making them susceptible to well-aimed small arms fire and thus defeating the whole purpose of the vehicle's armor.
Additionally, the commander's seat has an optical sight of sorts (viewed through the "binoculars-looking" thing visible in one of the screenshots attached) that aids in navigation and target spotting - that is currently, unlike the gun sights, inaccessible.
My issue with this is that in combat, when the shields are supposed to be closed, currently a BTR crew is blind - the tools intended to combat that are included in the model, but they don't work! Most you can rely on is the gunner, and that role has a lot more to handle than just navigation during combat, so it's by no means ideal.
Oh and one last note on the topic, the singular viewport on the tower of the BTR-70 is facing backwards - this aids in awareness for the gunner. The last two screenshots show its position inside and outside the vehicle.
Below I have attached several links of screenshots taken to demonstrate the issue, for reference purposes.

https://cdn.discordapp.com/attachments/753283468976455805/989562861082796032/unknown.png
https://cdn.discordapp.com/attachments/753283468976455805/989562893202776105/unknown.png
https://cdn.discordapp.com/attachments/753283468976455805/989562932750856232/unknown.png
https://cdn.discordapp.com/attachments/753283468976455805/989563451171016704/unknown.png
https://cdn.discordapp.com/attachments/753283468976455805/989563596591755264/unknown.png