If the rendering engine (the software drawing the text) is outdated or the font lacks the proper "GSUB" (Glyph Substitution) and "GPOS" (Glyph Positioning) tables, the text breaks, often resulting in disjointed characters or the dreaded "265x" box.

and Sirasa TV's on-demand services are migrating to H.265 for their catch-up TV features. Check your smart TV settings—enabling "HEVC" support can reduce buffering drastically.