(Please point out any mistakes, if I get too confused.)
I created a guild-only slash command, as follows:

bs = Slash(bot)
...
@bs.command(name= "test",
            description= "Foo bar", guild_ids= [880686520678371369],
            default_permission= False,
            guild_permissions= {880686520678371369: ui.SlashPermission(allowed= {ui.SlashPermission.USER: [687474789342117900]})}
)
async def tester(ctx):
    await ctx.respond("Test")
# 687474789342117900 is my user ID

I invoked this slash command. Immediately after that, the command gets removed from the list of other commands. All other commands continued to work, so I believe it is not a fatal bug. I tried looking into the module's code but I cannot find anything - I think it might be the bot wrongly deleting the command?