There's a patch for this at https://lists.sr.ht/~martijnbraam/public-inbox/patches/26259
I see the same thing on mobian/phosh and 1.3.0, where the memory usage ticks up constantly with a couple of MB per second.
The issue is apparently related to 59dde6bb74276f34c76d75d5fe801a0666c37b79 ("Fix crash on musl and clean up dependency"); memory usage is stable again after reverting the relevant part of that commit. I haven't dug any deeper than that.
Any ideas or pointers to what the issue with musl was, ~martijnbraam?