Desktop App: Unnecessary `More Unreads` bubble present

Description

Environment: 4.3 macOS desktop app, server rc.test 5.16-rc1

Steps:
1) Add rc.test server tab and log in (if not already present in desktop app)
2) Switch servers to community or similar and ensure you receive an in channel mention on rc.test
3) Switch to rc.test and observe unreads and `More Unreads` bubble

Expected: I did not expect `More Unreads` on rc.test since the whole LHS is in view.

Actual: There is a `More Unreads ↓` bubble on the bottom of the LHS , but no conversations below that it could be pointing to. See attached image.
I noticed this occasionally on community servers too, low on LHS `more unreads` bubble and while there were channels and DMs I can scroll down to reveal - none are unread

QA Test Steps

None

Status

Mana

None

Assignee

Unassigned

QA Assignee

None

Reporter

Jelena Gilliam

Epic Link

None

Fix versions

Mattermost Team

Apps

Sprint

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Labels

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QA Testing Areas

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GitHub Issue

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