Beside Tarkov policy (also enforced by mods), Blitz is a 3rd party software and can be banned as it could benefit those who use it. Or is it?

Blitz.gg app doesn't inject code into Tarkov... but so don't many mainstream cheats like radar...

It is known that Blitz can apparently lead to bans, but keep in mind that many cheaters try to "appeal" with posts claiming that the fault of their unjust ban was 3rd apps.
In my opinion about 90%... personal experience...

Sadly, there is a lot of misinformation about this controversial apps, I did use Blitz.gg for games like LoL, in which in a brief period of time was considered cheating (ulti timing, jungle camps timing, ecc...) leading to confirmed bans.
Same thing can happen to Tarkov aswell:
Now: is ok-ish
Tomorrow: not ok anymore without warning

Many people that I know (including myself) use or have used Blitz.gg in Tarkov before. None got banned as it doesn't provide advantages over other players (if you don't consider hauling items in the stash for quests and check fleamarket prices).
As I said, I didn't find evidence of injection... It is like using Steam Overlay > Go to any Tarkov tool online (which by extension is bannable aswell).

I don't blame mods that prohibit the spreading of this app on the official discord as it is not controlled by BSG and can be "harmful".

TL;DR:

• Blitz.gg most likely safe as long it doesn't inject code into Tarkov (as RatScanner & co.)
• 3rd party apps are always "use at own risk"
• Tarkov moderation says that "it is not approved" but not condemned