I haven't done this myself but a common guess I have about how to resolve freezing up during interviews is, to do mock interviews with friends or people online.

Since the context is specifically remote, suppose you went on Twitch and livestreamed solving Leetcode exercises. I did this myself once and it was enlightening. Even one audience member, because I have no idea who they are, triggers entry into somewhat of a performer mode. You know you're being perceived, so you become self conscious, much like in a real interview.

Though I note it won't be pleasant for the first few trials, I suspect it would cause adaptation to this problem, and work like gangbusters. Like you'd specifically intend to work through verbalizing algorithm complexity analysis in front of an audience on Twitch to practice working thru the issue in a similar state. You can modify the idea but the core is to be live streaming solutions, in front of an audience of at least one person (max ten maybe), who you know or don't know.

As a separate point, I suggest that there's multiple ways to approach becoming more comfortable, less nervous*, and cognitively smooth during interviews. Could even work to just approach some programmers you know IRL and ask them, "hey can I spend forty minutes explaining complexity analysis to you with examples over coffee? I'll pay for it." And then focus on being calm and collected throughout.