This is likely not something we (other users such as yourself) can fix. I am wondering if it is a system-level difference rather than something specific to Numbers. Best I can do is suggest some tests to see where the problem might be, which might lead to a possible workaround.
Can you copy/paste from other apps (other than Numbers) to WhatsApp and Telegram without losing formatting?
Can you copy/paste from Numbers to apps other than WhatsApp and Telegram without losing formatting (I tried TextEdit in RTF mode and Microsoft Word with no problem and also into Affinity Photo which pasted in as an image).
When pasting from Numbers into Telegram or WhatsApp, is it pasting as text or as an image? Pasting into Word or Textedit (into an RTF formatted document) creates a table and retains the formatting for me. Pasting into Affinity Photo it pastes as a low resolution image. Using New From Clipboard in the Preview app it pasts as a vector image that retains its resolution when enlarged. All retain the formatting.
Does it work better if you paste from Numbers into TextEdit (into an RTF formatted document) then copy/paste from there to Whatsapp/Telegram?
Do you have any "helper" apps running in the background that "enhance" the clipboard or the keyboard? Sometimes these apps are the cause of oddball problems.
