I think these are Icons rather than Emojis, and the cause may be a corrupt cache or cookie. Try deleting them as advised on this website. Most browsers have similar controls.
Rebooting doesn’t clear cookies should one happen to get mangled because they are stored on disc.
Although cookies usually time-expire automatically, could be a long wait, forever if the expiry date is damaged too. Zapping them manually forces the server to send a replacement.
The recent outbreak of Solar Flares, which grounded Airbus recently might be the cause. Unlike servers, laptops and workstations don’t have error correcting memory, so energetic particles occasionally cause malfunctions by flipping a bit. As do spikes on the mains, passing radio transmitters in taxis, or a neighbour running a VFD without an EMC filter!
Dave