Deprecate WOFF webfont format for UniversalLanguageSelector. Most browsers now support WOFF2: https://caniuse.com/woff2 Only IE11 needs WOFF format as of now and IE11 is being phased out. Also, sfntly - the tool we used to create .woff fonts is deprecated by upstream.
There is no need to make any code changes (AFAIK) in ULS. Removing .woff files from universallanguageselector/data/fontrepo/fonts should be enough.