Some pinned messages headers disappears from the top of some topics after moving from the topic to the topics list and back to the topic.
1 group of more than 1000, created before topics were enabled
2 enable topics
3 create 56 topics with 1st message pinned in each topic
4 some pinned messages headers starts to disappear from the top of some topics
Telegram Android 9.1.6 (29299), Xiaomi Mi 10T Pro, 12 (31)