Hmm.
This – Horizon — Quick-add modal caret icon rendering oversized on live view - #6 by tim_1 – may be a similar situation.
“Theme editor” applies CSS differently from live store and this can be a reason for what you see.
I guess Shopify has changed the logic around “compiled stylesheets” trying to optimize file sizes and it broke some things.
I’ve reported that problem to Shopify here – Horizon Theme AR Bug - #4 by tim_tairli - Online Store and Theme Development - Shopify Developer Community Forums
So, hopefully, the issue will be resolved and I’d rather recommend to wait…