Changes are almost entirely related to forced transition to another API version for Chrome version of this extensions. Minor fixes:

• Earlier zero-width space characters U+200B were added after timestamps. You may want to remove them from your notes, use search and replace for
  LAST_MODIFIED: [2021-09-18 Tue 01:23]<200b> 09/18/2021 01:23:46
• Only first <script> element with JSON-LD metadata was taken into account.
• Some permissions have been converted to optional ones.

Firefox version still uses Manifest V2 API as in earlier releases due to bugs in mv3 implementation. Significant modifications of code may cause new bugs.

Multiple tabs and cross-origin frames scenarios still require most dangerous <all_urls> permission, so I do not think the add-on has become more safe due to optional permissions. From my point of view, security model for browser extensions is still far from being consistent.

LinkRemark-0.3 version has only minor changes applicable to Firefox since 0.2.1
- More flexible handling of DOI URIs.
- More configuration options for org-protocol export method. New settings allow to launch external scheme handler without preview tab on privileged pages and experimental feature to detect problems with desktop-wide org-protocol handler may be enabled (it is better to switch it off when debugging is finished).
- Pre-selected export format and methods on preview and debug info page are adjusted. For some combination of values behavior was confusing.

The real reason of update is to keep version in sync with the one published in Chrome Web Store.