It literally threeshot two full hp squads. Read what I wrote. That is indeed a balance issue.
It's gf because at the time of the tank coming out that you know is coming you were chased all the way back to your base either twice with NOTHING to so much as scare it away or dissuade it? Yes that's TOTALLY a balance issue. "I didn't build any counters and it cost me the game, plz nerf" lay a fucking mine. Build a pak. Try.
If you had a clue of the game you would know that by the time the T70 arrives you usually have one Pak out (more Paks by that time will lose you the inf game). That Pak can cover one spot on the map. Any decent player will chase units with the T70 on the rest of the map and avoid the area the Pak is positioned. Now have fun moving your Pak around, keeping a snare nearby, not overextending the Pak and facing a unit that can kill your stuff in 10 secs.
In fact I might call the T70 the most imbalanced thing in the game currently. Can't think of bigger bs.