It’s Bolshevism that tries to blame every issue with the USSR on Stalin while ignoring that many of the structures that eventually led to Stalinism were present earlier on, when Trotsky and Lenin were at the helm. As a consequence, non-Leninist socialists, such as anarchists and autonomists, tend to dislike Trotsky and as a consequence Trotskyists.

For further reading on the anarchist position: https://theanarchistlibrary.org/library/iain-mckay-the-bureaucracy-in-exile

The Stalinists, in turn, view Trotsky as effectively sabotaging the revolutionary movement by sowing division and opposition to the vanguard.

Various sides heavily dislike the campism and entryism, and love of front groups prevalent among Trotskyist organisations.