[bug] switching themes in text "big mode" causes text to get bigger and bigger

[philiparvidsson]

I confirm that...

• I have searched the issue tracker, documentation, FAQ, Discourse, and Google, in case this issue has already been reported/resolved.

• I have read "How to Debug Issues", and will use it to provide as much information about this issue as possible.

• The issue can be reproduced on the latest available commit of Doom.

• The issue can be reproduced on a stable release of Emacs, such as 27, 28, or 29. (Unstable versions end in .50, .60, or .9x)

Expected behavior

switching themes should work in big mode as well, without causing humorously large fonts

Current behavior

in big mode, switching themes should work as usual. instead, it causes the font to grow a little bigger each time.

Steps to reproduce

1. press SPC t b to go into big mode
2. switch themes a number of times
3. look at screen

(maybe related: #5642)

System Information

.