The 6 series was when google introduced the tensor which is where the stereotype for worse battery life, worse performance, and less efficient radio come from.
I have a 6a too and for the price it’s fine, and I think a lot of the battery concerns are overblown, and for a budget phone competing with other budget phone devices tensor was great. That said the things that would make the tensor in the 7 bad are as present in if not more so in the 6a.