British born and bred, but obviously visually ‘foreign’-looking, and thus have had racist (ranging from uncomfortable to downright dangerous) encounters with a very small minority of people both in my personal and professional life. To those for whom the colour of my skin is a problem, I am viewed as non-British.
I don’t believe the union flag is considered to be racist. Same for the saltire and the Welsh dragon.
However, it depends on the context for the St George flag. Around the time of sporting events where England, rather than GB are competing, then no, not racist. A whole town festooned with the flag, no, I would not consider it to be racist. In these situations, I think it’s patriotic, brings the community together, and actually is rather lovely thing to see.
Unfortunately, whether we like to admit it or not, the St George flag has been co-opted by certain racist far-right groups. In combination with a constellation of other factors, I would find the display of the flag to be a marker that I might be under threat from an individual just from the colour of my skin.
I think there are usually enough other signifiers to show whether the intent of flying the flag is benign or potentially more dangerous.
(Just like for example itching is very common, and in the vast majority of cases is of no concern at all, but in combination with other features may be a sign of very serious pathology).
I think those commenting above are probably correct -maybe we should fly the flag more to reclaim it.