There is a issue of estimated time remaining while doing update it is stuck there

You must have a stable Wi-Fi connection.

Or connect to a PC with the latest version of iTunes installed.

Charge the battery to 50% or higher.

Turn off Battery saving mode.

Don't use a Hotspot.

Don't use VPN.

And make sure you have enough free space.

I am trying to restore my phone, but it has been stuck on Time remaining estimating