Just some info, and it applies to anyone else:
I notice you did a lot of keying-every-property in your animations, resulting in 200 timelines (the runtime object for each row you see in the dopesheet) and even over 300 timelines per animation. You can see this in the Metrics view in animate mode.
In skeletons like yours with well over 100 animations, this can get out of hand really quickly, making managing your keys more difficult (you're not sure which timeline is actually doing something, and you have to scroll around to find the items you actually want).
At runtime, these timelines add up to slow down both animation performance and load time (especially when using JSON) and makes file sizes worse.
In the context of having tested exporting your skeleton with only 10 animations from it and seeing around 11MB allocated, it seems believable that 200+ timeline-heavy animations in json format would add up to 200+MB of memory allocations.
So I tried exporting a binary file (.skel.bytes).
The GC Alloc went from 200+MB (json) down to 20+MB.
The json file is also 7MB, and the binary file is 2MB.
I believe this is the immediate answer to your current problem.
(1) Export your skeleton as Binary (extension: .skel.bytes).
(2) replace the SkeletonJSON field of your SkeletonData asset inspector with the .skel.bytes file.
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Of course, you can delete the .json file from your project after this.
regarding the runtime, I used the current spine-unity.unitypackage, then imported the spine-csharp-beta2.unitypackage from this thread: Noteworthy Spine-Unity Topics