The Germans were very luckly OTL, a huge number of breaks went their way, if Soviet leadership done things a little differently Barbarossa would've been harder for the Wehrmact.
The puges get a lot of press, but higher levels of command were relatively easy to replace with men like Zhukov & Konev ready to move up in rank. Far more serious was the shortage of officers at mid-level the Red Army had expanded rapidly and new officers had to be trained most of those men had been sent on 6 month courses and were then expected to take command & train others.
Also if the Red Army had been deployed better then perhaps most of the early encirclements wouldn’t have been possible for the Germans. Also if Stalin had believed some of the
months old Intel that the Germans were massing to attack the troops at the border could’ve been in a far
far higher state of readiness, also millions of reservists could’ve begin mobilize/train before the war even started.
Then you'd still have the million-odd well equipped Soviet troops in the Far East.
Thaking a;; that into account the Germans would’ve still pushed deep into Soviet territory at least taking the territories the USSR had taken back from Poland in 1941 (I just like to make the point the Poles took land from Russia by force themselves in 1920 and aren’t always the world’s hapless victims

) But it's likely the German momentum will have been sapped and their losses far greater than OTL..
By the time winter sets in the circa 1941 Red Army would still be mostly intact & battle-hardened(rather than the Red Army having to be rebuilt) and millions of fresh Soviet reserves will have poured intp the front-lines while the Germans are already near-fully mobilized.
The Soviet winter counter-attacks could be far more deadly.
We might snatch France or Italy.
A "Red Europe' will just lead to a faster USSR collapse anyway.
Not at all the USSR would be in much
much better shape in this scenario particularly if it takes both France and Germany the biggest economies in Europe, it also means the French overseas empire will be liberated earlier and red factions in those nations will be that much stronger ‘’Uncle Joe’’ will be a popular guy in say Syria & Algeria, Vietnam may also come under Ho Chi Minh’s.
The US will also lose it's most valuable trading partners in Europe unless it comes to terms with Stalin, Britain would be a de-facto 51st state by 1950. Also the USSR
itself will be in a much better shape as I don’t think the Soviets ever fully recovered from WW2.
I dont see the USSR ever collipsing in this case it'd domantie Euaisa, with hardly any direct threat by on it's borders & no NATO. Soviet efforts could focused to building the civilian economy, with it’s military simply looking to keep the satellite states in line. (Through France, united Germany & Italy had big enough home-grown Commie-movements to take care of themselves)