There's a tweet (1,564 likes as I write this) making the rounds that I think is at least half false. Since I don't have a Twitter/X account, I will reply here. The tweet says

Every day I get reminded of the story of how KPD and SPD members would clap when a member of the other party would come into the concentration camps

quote tweeting this tweet:

Not a fan of Tr*mp's to say the least but so far it is unclear there is anyone in his administration as monstrous as Biden's Middle East team.

The source for the KPD-SPD claim seems to be this earlier tweet from February (2,051 likes):

When the first concentration camps for political prisoners were created in Nazi Germany between 33-34, SPD deputy Gerhard Seger reported that KPD prisoners would cheer when the prison guards announced new prisoners of the SPD had arrived and vice-versa

When asked about the source, the author of that February tweet claimed that

You can find it in Seger's A Nation Terrorized, which is his personal report on one of the first concentration camps

A Nation Terrorized is the English title of Oranienburg. Erster authentischer Bericht eines aus dem Konzentrationslager Geflüchteten (my translation: Oranienburg: First Authentic Report from a Concentration Camp Escapee). The relevant passage reads, in full:

One evening at roll call, Sturmbannführer Krüger stepped before the ranks of prisoners and announced that the next day the "complete social democratic bigwig Fritz Ebert" would be delivered, this Marxist swine who belonged to the November criminals who had plunged Germany into disaster, and well, the SA would take care of this pig.

What happened after this speech with its ominous announcement at the end?

Loud cheers of "Bravo!" rang out from the ranks of the communist prisoners!

The communists in question, themselves victims of the SA charlatan standing before them, noisily took the side of their own party enemies, applauding when this National Socialist promised to take action against a Social Democrat!

I can find no other evidence of cheering or celebration of political opponents entering a concentration camp, and no other reports in A Nation Terrorized to that effect. So the original account seems wrong in a few ways:

• It suggests this type of thing happened multiple times, whereas there is only one report of it happening once
• It says it was reciprocal between both sides, whereas the report only mentioned the KPD doing it to a member of the SPD
• It states as a fact what one SPD politician (Seger) reported about his opponents (KPD)

Also, not to excuse the communists, but Fritz Ebert was not just any member of the SPD, he was the son of Friedrich Ebert who in the late 1910s had allied with conservative military forces and right-wing Freikorps units to violently suppress the communists, and who was plausibly most responsible for the murders of Rosa Luxemburg and Karl Liebknecht. The median SPD member would not have gotten the same reception. And finally, the events Seger reports happened in 1933 when the SPD-KPD rivalry was still fresh, and most of the Nazis' worst misdeeds had yet to happen -- for example, it was five years before Kristallnacht.