Change:
} public openLinkOccurrence(occurrence: LinkOccurrence, openToSide: boolean, fromUserGesture = false): void { <del> const { link } = occurrence; LinkOpener.get(this.editor)?.openLink(link.range, nls.localize('open', "Open Link"), () => { link.resolve(CancellationToken.None).then(uri => { </del> <ins> if (!this.openerService) { return; } </ins> <del> // Support for relative file URIs of the shape file://./relativeFile.txt or file:///./relativeFile.txt if (typeof uri === 'string' && this.editor.hasModel()) { const modelUri = this.editor.getModel().uri; if (modelUri.scheme === Schemas.file && uri.startsWith(`${Schemas.file}:`)) { const parsedUri = URI.parse(uri); if (parsedUri.scheme === Schemas.file) { const fsPath = resources.originalFSPath(parsedUri); </del> <ins> const { link } = occurrence; </ins> <del> let relativePath: string | null = null; if (fsPath.startsWith('/./')) { relativePath = `.${fsPath.substr(1)}`; } else if (fsPath.startsWith('//./')) { relativePath = `.${fsPath.substr(2)}`; } </del> <ins> link.resolve(CancellationToken.None).then(uri => { // Support for relative file URIs of the shape file://./relativeFile.txt or file:///./relativeFile.txt if (typeof uri === 'string' && this.editor.hasModel()) { const modelUri = this.editor.getModel().uri; if (modelUri.scheme === Schemas.file && uri.startsWith(`${Schemas.file}:`)) { const parsedUri = URI.parse(uri); if (parsedUri.scheme === Schemas.file) { const fsPath = resources.originalFSPath(parsedUri); let relativePath: string | null = null; if (fsPath.startsWith('/./')) { relativePath = `.${fsPath.substr(1)}`; } else if (fsPath.startsWith('//./')) { relativePath = `.${fsPath.substr(2)}`; } </ins> <del> if (relativePath) { uri = resources.joinPath(modelUri, relativePath); } </del> <ins> if (relativePath) { uri = resources.joinPath(modelUri, relativePath); </ins> } } } <ins> } </ins> <del> return this.openerService.open(uri, { openToSide, fromUserGesture, allowContributedOpeners: true, allowCommands: true, fromWorkspace: true }); }, err => { const messageOrError = err instanceof Error ? (<Error>err).message : err; // different error cases if (messageOrError === 'invalid') { this.notificationService.warn(nls.localize('invalid.url', 'Failed to open this link because it is not well-formed: {0}', link.url!.toString())); } else if (messageOrError === 'missing') { this.notificationService.warn(nls.localize('missing.url', 'Failed to open this link because its target is missing.')); } else { onUnexpectedError(err); } }); </del> <ins> return this.openerService.open(uri, { openToSide, fromUserGesture, allowContributedOpeners: true, allowCommands: true, fromWorkspace: true }); }, err => { const messageOrError = err instanceof Error ? (<Error>err).message : err; // different error cases if (messageOrError === 'invalid') { this.notificationService.warn(nls.localize('invalid.url', 'Failed to open this link because it is not well-formed: {0}', link.url!.toString())); } else if (messageOrError === 'missing') { this.notificationService.warn(nls.localize('missing.url', 'Failed to open this link because its target is missing.')); } else { onUnexpectedError(err); } </ins> }); }

Discussion:
The content of the line: Open definition does nothing !
Also happens on Mac with Cmd+Click. Makes it very difficult to navigate my documentation.
I believe this is a result of fixing Markdown has a link provider and a definition provider. However in this case, the definition provider returns since we are not on a reference link
revert of the bad change is up