Problems with AirPlay and subtitles

Hi I’m using an iPad Pro 12’’ to stream via Airplay to an Apple TV and suddenly the subtitles are appearing randomly, is working 30 seconds and then disappears and five minutes later appears during 20 seconds and repeating this issue all the time.
If I stop the Airplay, subtitles are working fine in the iPad.
Anyone can help me?

Y iPad is running iPad OS 14.3 and Apple TV (not 4K) the same,

Thanks