TYPO3 Core

Many years ago (at least since TYPO3 v3.3.0) a consideration of an optional field sectionIndex_uid was introduced in the page-record without adding this field to the default database structure.
If this field is present in a page-record anyway, the earlier linkData()-function and later on PageLinkBuilder prepend a hash-mark and a number.
Probably this feature was introduced by request from one or more TYPO3 instances. But this field never has become part of the default TYPO3 setup.
In TYPO3 v9 there are few lines code, which take account to this feature. But I noticed, this feature behaves wrong in some cases by appending multiple hash-marks to page links fx. for MENU objects.

I recommend to remove this feature, since I can not believe it is still in use and also ends up with wrong results.

My question is

Should these few lines of code removed instantly or should it be marked as deprecated first in current master, what I guess is the regular way.

How to test this feature

Create new field sectionIndex_uid to table pages, fill with any integer values

ALTER TABLE pages ADD sectionIndex_uid INT(11) NOT NULL DEFAULT '1';
UPDATE pages SET sectionIndex_uid = uid;

Use this setup as root typoscript template on any installation with subpages, where subpages can be normal, shortcuts and mountpoints

page = PAGE
page.10 = HMENU
page.10 {
    entryLevel = 0
    1 = TMENU
    1.NO = 1
    1.NO.allWrap = <li>|</li>
    1.wrap = <ul>|</ul>
    1.expAll = 1
    2 = TMENU
    2.NO = 1
    2.NO.allWrap = <li>|</li>
    2.wrap = <ul>|</ul>
    2.expAll = 1
    stdWrap.outerWrap = <h2>Default menu</h2>|
}