Try force upgrade

appcast.xml

@@ -1 +1 @@
-<?xml version="1.0" encoding="utf-8"?><rss version="2.0" xmlns:sparkle="http://www.andymatuschak.org/xml-namespaces/sparkle"><channel><title>ILSpy</title><description>For a detailed change log please go to xxx</description><language>en</language><item><title>ILSpy 8.0.0.7345</title><pubDate>Sat, 03 Jun 2023 16:28:52 +02:00</pubDate><enclosure url="https://github.com/icsharpcode/ILSpy/releases/tag/v8.0/ILSpy_Installer_8.0.0.7345.msi" sparkle:version="8.0.0.7345" sparkle:shortVersionString="8.0.0" length="4456448" sparkle:os="windows" type="application/octet-stream" sparkle:signature="921UgLifNi8t3VTJCeMGZtQGPLm+NsmkyY3wr5zdPKPektSEKYxgmIzAev48RcJXw7htOZPD6q7zAYgcjS0HDA==" /></item></channel></rss>
+<?xml version="1.0" encoding="utf-8"?><rss version="2.0" xmlns:sparkle="http://www.andymatuschak.org/xml-namespaces/sparkle"><channel><title>ILSpy</title><description>For a detailed change log please go to xxx</description><language>en</language><item><title>ILSpy 8.0.0.7400</title><pubDate>Sat, 03 Jun 2023 16:28:52 +02:00</pubDate><enclosure url="https://github.com/icsharpcode/ILSpy/releases/tag/v8.0/ILSpy_Installer_8.0.0.7400.msi" sparkle:version="8.0.0.7400" sparkle:shortVersionString="8.0.0" length="4456448" sparkle:os="windows" type="application/octet-stream" sparkle:signature="921UgLifNi8t3VTJCeMGZtQGPLm+NsmkyY3wr5zdPKPektSEKYxgmIzAev48RcJXw7htOZPD6q7zAYgcjS0HDA==" /></item></channel></rss>

appcast.xml.signature

@@ -1 +1 @@
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+k/C3DCjxz8gSV6fPUcfq9BnUKB5lHwT3+bCklhMYsPM31GY4UTJXgwETgRNxjeyUnBf4I8ax/BQ2U+b2DD0yCQ==