BUG #18092: Unexpected Result by enable_seqscan

The following bug has been logged on the website:

Bug reference: 18092
Logged by: Jinsheng Ba
Email address: bajinsheng(at)u(dot)nus(dot)edu
PostgreSQL version: 15.4
Operating system: Ubuntu
Description:

The same query returns different results when enable_seqscan is changed:

CREATE TABLE t0(c0 FLOAT);
INSERT INTO t0(c0) VALUES(0.8);
CREATE VIEW v0(c0) AS (SELECT 1);
CREATE INDEX i0 ON t0(c0);
UNLISTEN *;
ANALYZE;
INSERT INTO t0(c0) VALUES(0.1);

SET enable_seqscan=on;
SELECT DISTINCT ON (v0.c0) t0.c0 FROM v0, t0; -- {0.8}
SET enable_seqscan=false;
SELECT DISTINCT ON (v0.c0) t0.c0 FROM v0, t0; -- {0.1}

Reproduction:
docker run -p 5432:5432 -e POSTGRES_PASSWORD=root -it postgres:latest
psql "postgresql://postgres:root(at)localhost:5432"