Umbrella issue for 26.0 testing. Please help testing on a wide variety of supported platforms, as well as interaction with different software.

Let us know which version you tested on which operating system.

If you find an issue, please search Github for known issues first and then open a new Github issue.

*This meta issue should not be used to report bugs, as a single thread makes it impossible to track more than one topic.*

See [26.0 Draft Release Notes](https://github.com/bitcoin-core/bitcoin-devwiki/wiki/26.0-Release-Notes-Draft) for a list of changes.

See here for the testing guide: https://github.com/bitcoin-core/bitcoin-devwiki/wiki/26.0-Release-Candidate-Testing-Guide.
static_assert((MAX_BLOCK_SIZE_BYTES & (ELEM_ALIGN_BYTES - 1)) == 0, "MAX_BLOCK_SIZE_BYTES needs to be a multiple of the alignment.");
    /**
     * Size in bytes to allocate per chunk
     */
    const size_t m_chunk_size_bytes;
    /**
     * Contains all allocated pools of memory, used to free the data in the destructor.
     */
    std::list<std::byte*> m_allocated_chunks{};
    /**
     * Single linked lists of all data that came from deallocating.
     * m_free_lists[n] will serve blocks of size n*ELEM_ALIGN_BYTES.
     */
    std::array<ListNode*, MAX_BLOCK_SIZE_BYTES / ELEM_ALIGN_BYTES + 1> m_free_lists{};
    /**
     * Points to the beginning 
     */
    std::byte* m_available_memory_it = nullptr;
    /**
     * Points to the end 
     *
     * That member variable is redundant, and is always equal to `m_allocated_chunks.back() + m_chunk_size_bytes`
     * whenever it is accessed, but `m_available_memory_end` caches this for clarity and efficiency.
     */
    std::byte* m_available_memory_end = nullptr;
    /**
     * How many  index
     * into m_free_lists. Round up for the special case when bytes==0.
     */
    [[nodiscard]] static constexpr std::size_t NumElemAlignBytes(std::size_t bytes)