v3.7.3

Fixed

• AppendFormat with an unclosed { appended the whole format string a second time ("Hello {0} and {" gave "Hello 1Hello {0} and {"). Now only the not yet written rest is appended.
• TrimPrefix and TrimSuffix with a culture-sensitive StringComparison removed value.Length characters instead of the actual match length, so ignorable or composed characters left the wrong content behind or made TrimSuffix throw.
• Insert(int, ReadOnlySpan<char>) produced wrong content when the inserted span points into the builder itself (e.g. builder.Insert(0, builder.AsSpan(1))).
• Interpolated strings passed no format to types that implement IFormattable but not ISpanFormattable, so $"{value:X}" called ToString() instead of ToString("X", null). Applies to ValueStringBuilder and FixedSizeValueStringBuilder.
• AppendSpan with a negative length decreased Length before throwing. It now throws an ArgumentOutOfRangeException up front and leaves the builder untouched.
• Insert<T> for ISpanFormattable values grows like Append<T> when the formatted value exceeds the default buffer size of 36 characters, instead of throwing an InvalidOperationException. A custom bufferSize still throws when it is too small.
• Insert<T> stack-allocated the caller-provided bufferSize unbounded, so a large value crashed the process with a stack overflow. Sizes above 256 characters are now rented from the ArrayPool.