Image display in unstable warning message

Hi Team,
I’m having an alert problem with images, it works unstable.
Sometimes the image is displayed, but sometimes the alert is not sent.
I see the following error appear:
lvl=eror msg=“Failed to send webhook” logger=alerting.notifier.telegram error=“Post “https://api.telegram.org/bot1481361358:AAFrOLtySZJ6LFwsLMhgXvQugLNgcnfIyo4/sendPhoto”: context deadline exceeded (Client.Timeout exceeded while awaiting headers)” webhook=Test-Alert
t=2021-08-09T09:07:12+0700 lvl=eror msg=“failed to send notification” logger=alerting.notifier uid=BXAQ12gnz error=“Post “https://api.telegram.org/bot1481361358:AAFrOLtySZJ6LFwsLMhgXvQugLNgcnfIyo4/sendPhoto”: context deadline exceeded (Client.Timeout exceeded while awaiting headers)”
t=2021-08-09T09:07:12+0700 lvl=eror msg=“failed to send notification” logger=alerting.notifier uid=BXAQ12gnz error=“Post “https://api.telegram.org/bot1481361358:AAFrOLtySZJ6LFwsLMhgXvQugLNgcnfIyo4/sendPhoto”: context deadline exceeded (Client.Timeout exceeded while awaiting headers)”
Can someone please assist me? it took me quite a while but didn’t find the solution!!!

I am using grafana v8 on ubuntu 20.04!

Are you using the legacy alerting system or the new Unified Alerting system that was shipped with Grafana 8 but is still behind a feature toggle?

I’m still using grafana’s alert feature since v7 and it hasn’t changed.
Problems encountered after I upgraded to v8

Can anyone help me with this problem?