We see the assertion while running gtest since 2025-11-10 in this environment:
Intel(R) Xeon(R) Platinum 8260 CPU @ 2.40GHz, 16 cores, 31G, Windows Server 2016 , 64 bit Build 14393 (10.0.14393.8519)

# Internal Error (openjdk-jdk-windows_x86_64-dbg\jdk\src\hotspot\cpu\x86\gc/z/zAddress_x86.inline.hpp:35), pid=37128, tid=26420
# assert(index == 0 || is_power_of_2(index)) failed: Incorrect load shift: 15

Stack trace is currently broken in our environment (debug info of output_openjdk26_stage_dbgU_ntamd64\jtreg\test\hotspot\gtest\server\jvm.dll insufficient). We can update in case we can get that fixed.

We also got many errors:
[----------] 1 test from ZAddressTest
[ RUN ] ZAddressTest.is_checks_vm
openjdk-jdk-windows_x86_64-dbg\\jdk\\test\\hotspot\\gtest\\gc\\z\\test_zAddress.cpp(186): error: Value of: ZPointerLoadGoodMask != 0
  Actual: false
Expected: true
...
openjdk-jdk-windows_x86_64-dbg\\jdk\\test\\hotspot\\gtest\\gc\\z\\test_zAddress.cpp(226): error: Expected equality of these values:
  ZPointer::is_marked_any_old(ptr)
    Which is: false
  same_old_marking
    Which is: true
...