This is related to T200206 but not the same.
Although TemplateStyles stylesheets are deduplicated at the end, they still count toward the unstrip post-expand size of the page. If a template using that stylesheet is transcluded many times on a page, it could exceed the unstrip post-expand size limit.
A fix not possible on WMF wikis is to create a deduplication template using the Variables extension. Replace the templatestyles tag with {{Deduplicate | name=Item | 1=<templatestyles src="Item/styles.css"/> }}. The content of the deduplication template would be {{#varexists: {{{name|}}} | | {{{1|}}} {{#vardefine:{{{name|}}}|T}} }}, which will ensure that the tag is only included once on the page. This is used on Blue Archive Wiki.
Another workaround is to put the content of the stylesheet in Common.css or a gadget loaded conditionally only for pages in a tracking category inserted by the template.