Double room and user mentions when <a> object text contains another HTML object.

[0xDEADCADE]

Describe the bug Sending the following as HTML causes SchildiChat Android to display the room/user mention twice. <a href="https://matrix.to/#/%23android%3Aschildi.chat"><img src="mxc://supercable.onl/fVWStgRAiMCZVnCTOfjCYFnL" height="24"> SchildiChat Android</a>

To Reproduce Steps to reproduce the behavior:

1. Send an event of type m.room.message with this content:

   {
   "body": "<a href=\"https://matrix.to/#/%23android%3Aschildi.chat\"><img src=\"mxc://supercable.onl/fVWStgRAiMCZVnCTOfjCYFnL\" height=\"24\"> SchildiChat Android</a>",
   "format": "org.matrix.custom.html",
   "formatted_body": "<a href=\"https://matrix.to/#/%23android%3Aschildi.chat\"><img src=\"mxc://supercable.onl/fVWStgRAiMCZVnCTOfjCYFnL\" height=\"24\"> SchildiChat Android</a>",
   "msgtype": "m.text"
   }

2. See the room mention appear twice, whereas on other clients it appears once

Expected behavior The room mention should appear once

Screenshots

Smartphone (please complete the following information):

• Device: OP Nord
• OS: Android 12, SuperiorOS Vanilla

Additional context

• App version: 1.4.34.sc58 [40100910] (F-9e380ac7)
• Store: SpiritCroc's F-Droid
• Homeserver: matrix.deadca.de

Upstream relevance

• Does this issue exist in Element Android? This issue does not exist in Element Android (1.4.32, 1.4.34)
• If this issue exists in Element Android, please also link the corresponding bug report (create a new one if it doesn't exist yet)

[SpiritCroc]

Haven't figured out what is happening there yet, but seems to be caused by the combination of the pills processor and the inline image plugin - if one of them is disabled, it looks ok. If the pills processor does nothing, it also looks ok. If the image plugin does a minimum of loading no image, it still breaks.

[SpiritCroc]

No more pills for nested inline images to fix this case, to be included in the next release.